[原创]Qt动态进度条根据输入值改变

首先看下效果图:

核心部分代码如下:

psshowslider.h

class psshowslider : public QFrame
{
    Q_OBJECT

public:
    explicit psshowslider(QWidget *parent = 0);
    ~psshowslider();
    //设置最大值
    void setMaxValue(double maxvalue);
    //得到最大值
    double getMaxValue();

    //设置最小值
    void setMinValue(double minvalue);
    //得到最小值
    double getMinValue();

    //设置值
    void setValue(double value);
    //取得值
    double getValue();

protected:
    void paintEvent(QPaintEvent *);

private:
    Ui::psshowslider *ui;
    //滑动条最大值
    double maxvalue;
    //滑动条最小值
    double minvalue;
    //设置显示的值
    double value;

};

psshowslider.cpp里面主要是paintEvent()函数的重写.

void psshowslider::paintEvent(QPaintEvent *) {
    QPainter painter(this);
    //移动坐标系
    painter.translate(20, height() / 2);
    QPen pen(Qt::white, 3, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin);
    painter.setPen(pen);
    painter.drawLine(0, 40, 0, -40);

    //画上边直线
    painter.drawLine(0, -30, 320, -30);
    //画下边直线
    painter.drawLine(0, 30, 320, 30);
    //画上下直线刻度以及文字
    int num = 1;
    int x, y;
    QPen pen2(Qt::white, 2, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin);
    QPoint point;
    painter.setPen(pen2);
    for (; num < 21; num++) {
        x = 15 * num;
        if (num % 2 == 0) {
            y = -20;
            point.setX(x - 8);
            point.setY(y + 10);
            painter.drawText(point, QString::number(50 * num));
        } else {
            y = -25;
        }
        painter.drawLine(x, -30, x, y);
    }

    //设置线性渐变
    QLinearGradient linearGradient = QLinearGradient(0, 0, 300, 0);
    linearGradient.setColorAt(0.0, Qt::cyan);
    linearGradient.setColorAt(0.6, Qt::yellow);
    linearGradient.setColorAt(1, Qt::red);
    //设置画刷
    QBrush qsh(linearGradient);
    painter.setBrush(qsh);

    painter.setPen(Qt::cyan);
    //画矩形
    painter.drawRect(0, -5, this->getValue() / this->getMaxValue() * 300, 34);

}

每次当类属性value改变之后,只需要调用类的update()方法或者repaint()方法即可.

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